Sinofsky's rise to power started with earning the trust of Bill Gates.

Sinofsky was born in New York and spent most of his childhood in Orlando, Florida. He graduated from Cornell University with honors, then got his master’s in computer science from the University of Massachusetts, Amherst in 1989.

Then he went straight to work at Microsoft.

When he arrived, it immediately felt like home. He writes in a blog post from 2005:

“It was incredibly cool when I showed up at Microsoft—I was 23 years old and ready to go to work. I had no friends in Seattle. My family was 3000 miles away. I lived in an apartment within walking distance from Microsoft that had a pool where beautiful people hung out. I had disposable income for the first time in my life. I was ready to be one of those cool people on Melrose Place, except I quickly found out that the work at Microsoft was way cooler than sitting by the pool … It was our own Melrose Place, but with C++ code instead of an advertising agency. It had COMDEX instead of Venice Beach.”

APBill Gates, around the time Sinofsky was working for him.

A few years after he started, Sinofsky got a big break when Bill Gates chose him to be one of his technical assistants. There, the two formed a bond of trust that persists to this day.

In 1994, on a visit back to his alma mater, Sinofsky was stuck at Cornell during a snowstorm. While he was there, he saw how Cornell was taking advantage of the Internet with email for undergraduates and online course listings.

He dashed off an email to Gates with the subject line “Cornell is WIRED!” emphasizing how important the Internet was becoming.

Sinofsky’s email kicked off a chain of events that eventually led Bill Gates to write his famous “Internet Tidal Wave” memo in 1995. That memo caused every Microsoft product group to start building Internet connections into their products and paved the way for Internet Explorer to be bundled into Windows, kicking off the consumer Internet revolution. (It also kicked off the antitrust lawsuit that would mire Microsoft for almost 10 years in the late 1990s).

Later, when Sinofsky took over the Office group, his ability to get product releases out on time made him indispensable.

One former Microsoft employee recalls a time when Sinofsky was being particularly stubborn about doing what Gates wanted the Office group to do. Gates brought up the possibility of replacing him.

This former employee, who heard the conversation, says, “The pushback was that Office was so important from a revenue standpoint, and Steven was so important to Office delivering that revenue, that they couldn’t fire him.”

Eventually, Gates came around to that point of view. Sinofsky is now almost untouchable, and has occasionally used that status to get his way.

A different former employee tells us that Sinofsky once threatened to quit when he wasn’t given a desired assignment. Gates said that he couldn’t imagine Microsoft without Steven. As consolation, Microsoft's leadership at the time put some other products under Sinofsky’s control.

Steve Ballmer also trusts Sinofsky because he’s demonstrated an ability to deliver updates to his products on a very tight three year schedule.

Here’s why that matters so much.

Microsoft’s business depends on big companies buying long-term license agreements — at least $20 billion of Microsoft’s more than $70 billion a year comes from these agreements. These deals tend to run on a three year cycle, and include the right to upgrade to new product versions that come out during that term.

If Microsoft fails to deliver a new version of the product within three years — as happened with Windows Vista and has happened with other products, like SQL Server — customers wonder “why did we buy a license agreement?” That makes selling renewals and upgrades a lot harder the next time around.

This is Ballmer’s bread and butter. He is said to know and understand almost every aspect of Microsoft’s licensing rules, and exactly how changes are going to affect revenues in any given product group.

Most executives at Microsoft are “Bill people” or “Steve people.” Sinofsky is both.